Settlement and deflection of precast grade crossing were causing highway pavements to deteriorate. The crossing is owned and maintained by the large business park it serves, is used by CSX, and crosses a major highway maintained by FDOT. Exploratory geotechnical investigations determined that the soil under the crossing had sufficient bearing capacity. However, a void had developed under the crossing, which allowed water to pool under the slabs. The slabs deflected under vehicle & rail traffic, which pumped the sandy backfill material out from under the slabs.
The adjacent asphalt had failed, which channeled water into the void below the panels, causing the problem to worsen.
This Florida grade crossing repair had to quickly and thoroughly address the voids and settlement of the panels. Additionally, the material used for void filling and lifting needed to be resilient under dynamic loading from the train and vehicular traffic, and capable of performing well in saturated environments.
High-density polyurethane grouting to stabilize and lift the affected precast grade crossing panels. Polyurethane grouting is far superior to mudjacking because it allows for rail traffic during the repair and immediate resumption of road traffic. Because the adjacent asphalt had significantly deteriorated, the immediate return to service allowed full-size paving equipment to traverse the crossing immediately after the polyurethane grouting was done.
CJGeo modular grade crossing repair crew filled the voids and corrected settlement in fewer than four hours. Milling and paving of the adjacent roadway were done the following day. The roadway and rail opened up immediately afterward.